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memory calculation

Hi,

I am running a 64 bit RHEL 4 in one of mymachines with 8 Gb of physical memory.But when I run the top command, it outputs as below:

PHP Code:





Mem:   8165428k total,  8109988k used,    55440k free,    65772k buffers
Swap:  4194296k total,   135596k used,  4058700k free,  6739936k cached

On calculation, it shows it has only 7.7 Gb of memory if I calculate ( using 1 Gb = 1024*1024 Kb).

Where is .3Gb gone ? Again, it is a 64 bit machine..so should see all 8Gb. Is it mistake of top command calculating 1Gb=1024*1000Kb ??

Is some reserved for on board graphics ?

BTW, you need to be careful with your terminology.
1Gb = 1 gigabit
1GB = 1 gigabyte

One is 8 times larger than the other.
Same applies for MB, KB, TB, PB.